The invention relates generally to micro-electromechanical devices, and more particularly, to integrated micro-electromechanical switches.
Micro-electromechanical system (MEMS) devices have a wide variety of applications and are prevalent in commercial products. One type of MEMS device is a MEMS switch. A typical MEMS switch includes one or more MEMS switches arranged in an array. MEMS switches are well suited for applications including cellular telephones, wireless networks, communication systems, and radar systems. In wireless devices, MEMS switches can be used as antenna switches, mode switches, transmit/receive switches, and the like.
Typical MEMS switches use an electroplated metal cantilever supported at one end and an electrical contact arranged at the other end of the metal cantilever. A control electrode is positioned below the metal cantilever. A direct current (“DC”) actuation voltage is applied across the control electrode to the metal cantilever forcing the metal cantilever to bend downward and make electrical contact with a bottom signal trace. Once electrical contact is established, the circuit is closed and an electrical signal can pass through the metal cantilever to the bottom signal trace.
One type of MEMS device is a MEMS radio frequency (RF) switch. MEMS RF switches are used for wireless devices because of their low drive power characteristics and ability to operate in radio frequency ranges. However, a problem frequently occurs within MEMS RF switches when a significant RF voltage is applied between a beam electrode and a contact electrode. Such a voltage may couple on to the control electrode and self-actuate the switch. In other words, these MEMS switches typically suffer from a problem where the cantilever beam within the switch may actuate at the “OFF” state (self-actuation) due to the high voltage RF signal. Thus, the high voltage RF signal produces adequate electrostatic force to pull down the switch beam and cause failure.
Another drawback associated with the MEMS RF switches is the generation of a “hot switch” voltage based on a residual energy generated at the contact electrodes. Such a residual energy may be generated based on a residual voltage from the system and coupled energy from a gate line to the contact electrodes.
There is a need for an enhanced system that overcome drawbacks associated with a voltage standoff capability and generation of a hot switch voltage.